[Abstract Title]. - Society for Neuroscience

Abstract: The dominant approach to modeling relationships between experience, behavior, and
brain dynamics is to acquire brain imaging data during presentation of a sequence of stereotyped
classes of stimuli that elicit a small repertoire of participant behavioral responses, usually small
finger movements. Researchers then average brain dynamics time locked to these stimulus or
response classes and compare them by computing differences -- the method of planned
comparisons. However, there is no guarantee that the dynamics produced by the brain during the
experiment are solely or chiefly evoked by these event classes, or that each event class elicits
only one type of brain response. The size, latency, and type of brain activity time locked to
sensory and behavioral events may be linked to the detailed nature of the event, its relevance to
the participant task, and/or to the exact context in which the event occurs. The brain may be said
to continually „respond to the challenge of the moment‟ so as to maximize participant rewards
and minimize penalties. But what is the nature of the brain‟s „challenge of the moment? What
aspects of the event and its context determine the nature and size of the observed brain
dynamics? Here we decomposed high-density scalp EEG data recorded during performance of a
difficult continuous performance working memory task with auditory feedback („two-back with
feedback‟) using independent component analysis (ICA), then converted the separated signals
around feedback events of components associated with probable brain sources into normalized
log spectrograms. To each spectrogram we appended a vector of context indicator variables, each
the (yes/no) answer to a question about the trial itself or about preceding or succeeding trials.
Decomposing this fused data by ICA produced a number of „independent context factors‟
combining a time/frequency log power template, plus a vector of context factor loadings, with a
vector of multiplicative weights giving the relative polarity and strength of the factor on
component spectral changes during the trial. The method revealed overlapping EEG spectral
changes in many cortical source components that were associated with current or past reward,
penalty, and neutral feedback, or with future performance.
Disclosures: S. Makeig , None; J. Onton, None.
Poster
288. Working Memory: Disorders, Genes and Connectivity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 288.28/RR35
Topic: F.01.f. Working memory
Support: Johnson O'Connor Research Support Corporation
Title: Gender differences in correlations of regional white matter integrity with intelligence
factor scores